A method for forming a self-aligned contact in a semiconductor device which can reduce process failures and a method for manufacturing a semiconductor device that includes the self-aligned contact are provided. A self-aligned contact hole is formed in an interlayer dielectric film to expose a portion of the substrate between conductive structures formed thereon. A buffer layer is formed on a sidewall of the self-aligned contact hole, on the bottom of the self-aligned contact hole, and on the interlayer dielectric film such that the thickness of the buffer layer at an upper portion of the self-aligned contact hole is greater than the thickness of the buffer layer at the bottom of the self-aligned contact hole. After removing the portion of the buffer layer on the bottom of the self-aligned contact hole, a contact is formed in the self-aligned contact hole to make contact with the substrate.